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Science on flu shot effectiveness doesn't support flu shot policies: researcher

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  • Science on flu shot effectiveness doesn't support flu shot policies: researcher

    Science on flu shot effectiveness doesn't support flu shot policies: researcher
    19:16:27 EDT Oct 26, 2006

    Canadian Press: HELEN BRANSWELL

    TORONTO (CP) - There isn't enough proof that flu vaccine is effective to support public programs advocating widespread use of flu shots, a controversial vaccine epidemiologist is suggesting. <!-- CPPara1End--> <!--updated p--> <!--updated para--> <!-- CPPara2-->In a commentary being published Friday in the British Medical Journal, Dr. Tom Jefferson argues that large-scale, long-term randomized controlled trials - the gold standard for generating scientific evidence - should be "urgently" undertaken to see if flu shot programs are achieving their goals of lowering rates of cases and deaths.
    <!-- CPPara2End--> <!--updated p--> <!--updated para--> <!-- CPPara3-->"There's a huge gap between policy and evidence," Jefferson, who is co-ordinator of the Cochrane Vaccines Field in Rome, said in an interview Thursday.
    <!-- CPPara3End--> <!--start of p-->"I think the whole thing should be looked at again. That's what I recommend."
    <!--start of p-->The Cochrane Vaccines Field is a division of the Cochrane Collaboration, an international not-for-profit network aimed at promoting evidence-based health care. The collaboration funds and publishes Cochrane reviews, a highly specialized form of scientific analysis that amalgamates the findings of high-quality studies on a topic.
    <!--start of p-->Jefferson didn't seem to feel funding agencies might balk at the notion of spending millions of dollars to go back to Square 1 to research the efficacy and safety of a public health intervention that's been in use for decades.
    <!--start of p-->"I would have thought they (the trials) would be a lot cheaper than continuing with a program that may not work."
    <!--start of p-->He also suggested there may be compelling ethical arguments in favour of doing this work, noting it could be unethical to give flu shots to people if it isn't clear the vaccine works.
    <!--start of p-->But Dr. Theresa Tam of the Public Health Agency of Canada took the flip side of the same argument, saying from an ethics point of view it might be impossible to enrol seniors in a study where some get a placebo instead of a shot.
    <!--start of p-->In the world of clinical trials it is unethical - and not permissible - to withhold a drug, vaccine or other treatment if it's been proven to be effective either in treating or preventing a condition.
    <!--start of p-->"We certainly believe, looking at all of the evidence, that for the elderly - who are at high risk - even if the vaccine effectiveness is lower (than in healthy adults), it's still worth it, said Tam, director of the agency's immunization and respiratory infections division.
    <!--start of p-->In the journal, Jefferson argued too few good quality trials have been conducted to be certain flu shots are worth the time, effort and cost of flu vaccine programs.
    <!--start of p-->His argument is bound to stir up ire in the community of scientists and public health authorities who deal with influenza, particularly now as flu clinics throughout the Northern Hemisphere are just starting their annual vaccination efforts.
    <!--start of p-->"That the BMJ would consider publishing an editorial from somebody saying that we should be thinking about not vaccinating at-risk people for influenza is a really bad thing," said Dr. Allison McGeer, an infectious diseases specialist at Toronto's Mount Sinai Hospital.
    <!--start of p-->Jefferson and colleagues at the vaccines field have in the past couple of years published Cochrane reviews challenging the efficacy of flu vaccine in children and in the elderly. The mere mention of his work provokes heated reactions in some influenza circles.
    <!--start of p-->That may be in part because the Cochrane approach places limited value on data not generated through randomized controlled trials. While other scientists acknowledge those studies are best, they note it isn't always possible to conduct them, and that an accumulation of other forms of evidence can make a persuasive case as well.
    <!--start of p-->McGeer pointed to a complaint in Jefferson's commentary about the lack of good, comparative data on the safety of flu shots.
    <!--start of p-->"How can you say that we don't have a safety record when we give 20 million vaccinations a year?" she asked with exasperation in her voice.
    <!--start of p--> Flu shot advocates do admit the vaccine isn't as effective as they would like.
    <!--start of p-->Efficacy varies from year to year, depending on how well matched the strains in the shot are to those circulating and causing disease. And the amount of protection depends on age - the shots provoke a better immune response in healthy adults than they do among the elderly, whose immune systems are on the wane.
    <!--start of p-->"Even a vaccine that is not as effective as we would like could still have a substantial benefit," said Tam, who noted that as far as the agency is concerned, there is enough evidence to conclude vaccinating people against the flu lowers the annual toll of the disease.
    <!--start of p-->Conducting the types of trials Jefferson advocates wouldn't be easy, given that the amount of flu activity varies from year to year, the vaccine isn't always a perfect match for circulating strains and different ages respond differently to the shots.
    <!--start of p--> Tam said that while the public health agency continues to conduct studies on the efficacy of flu vaccine, the type of abrupt re-examination of policy Jefferson is advising isn't in the cards here.
    <!--start of p-->"We certainly think that very large scale, multi-year randomized controlled trials . . . is just not that feasible for most public-health programs."

    <center>? The Canadian Press, 2006</center>